The present invention relates, in general, to semiconductor devices, and more particularly, to semiconductor devices with improved breakdown voltage.
In the past, the semiconductor industry has utilized various techniques to provide semiconductor devices with low on-resistance, high breakdown voltage, and low cost. One common technique is to use a reduced surface field technique, commonly referred to as RESURF, to attempt providing semiconductor devices with improved breakdown characteristics. One type of RESURF generally requires counter doping portions of the drift region in order to form depletion regions that reduce electric fields at the surface of the channel region. One problem with these RESURF techniques is that the doping within the counter doped areas must be balanced with other doping levels within the device. Consequently, the device becomes very sensitive to process variations, thereby reducing the yield and increasing the cost of the device.
Additionally, the doping within the counter doped areas must not move or diffuse during subsequent manufacturing operations. This makes it difficult to integrate other semiconductor devices onto the same substrate, thereby increasing the overall cost of semiconductor devices. Furthermore, forming the counter doped areas requires additional masking and implanting operations thereby resulting in higher manufacturing costs for the semiconductor device.
Accordingly, it is desirable to have a semiconductor device having an improved breakdown voltage, low on-resistance, low cost, and that is integratable with other semiconductor devices.